Defining Extinction Peaks Of Various Types Of MXenes For Photothermal Therapy And Other Biomedical Applications

MXenes is a novel class of two-dimensional materials, which have gained significant popularity across various applications [1]. Among their diverse involvements, MXenes have found increasingly extensive use in the biomedical fields. One promising avenue is photothermal therapy, where MXenes can serve as efficient light-to-heat energy transfer photosensitizers. For instance, we showed that Ti₃C₂ MXene was suitable for the development of advanced photothermal (PTT) protocols with a pulsed 1064 nm near-infrared laser [2]. However, to achieve an optimal energy transfer, it is crucial to identify the wavelength absorbance peak that maximises energy transfer efficiency. Here, we present the method of UV-VIS spectroscopy in a multichannel µDrop plate along with Ti₃C₂ and Nb₄C₃ MXene spectra.

Our experimental setup involved a wide-spectrum 360 - 2600 nm stabilized tungsten-halogen light source (Thorlabs, SLS201L) and a spectrometer (AvaSpec 2048), which were connected through the optical fibre system to the 3D printed cuvette holder with a cuvette inside filled with a tested solution. Specifically, we investigated Ti₃C₂ and Ni₄C₃ MXenes. We also used Thermofisher scientific Multiskan SkyHigh with quartz µDrop Duo attachment to validate our results.

After acquiring the extinction spectra for each MXene, we calculated the mean absorbance for various concentrations and built the trendline of the extinction. Next, we extracted the extinction peaks by providing a derivative analysis of the trendline (dExtinction/dWavelength = 0).

Our findings identify the optimal wavelength values for photothermal therapy (PTT) using Ti₃C₂ MXene, a material extensively utilized in biomedical research. We detected two extinction peaks at 309 nm and 780 nm. In contrast, Nb₄C₃ MXenes exhibited no observable peaks. This data shows that Ti₃C₂ MXene can be used with a 780 nm laser to reach the maximum efficiency of photothermal therapy. We have also shown the method of UV-VIS spectroscopy of MXene solution in multichannel µDrop plate in small (only 2-5 µl) amounts of solution.